1. Field
Apparatuses and methods consistent with the exemplary embodiments relate to a waveguide of a multi-layer metal structure and a manufacturing method thereof, and more particularly, to a technology of designing a waveguide in a multi-layer metal structure where a plurality of metal layers are stacked on a substrate and a plurality of insulating layers are respectively formed between the respective metal layers.
2. Description of the Related Art
Studies are currently underway on various applications for a millimeter-wave band having frequencies higher than 60 GHz. Representative applications for the millimeter-wave band include a Local Multipoint Distribution Service (LMDS), a Wireless High Definition Multimedia Interface (HDMI), a Wireless Local Area Network (LAN), an Automotive Radar, and Satellite Communications.
An important factor in implementing a millimeter-wave circuit is the design of a waveguide. In a millimeter-wave band, unlike a low-frequency band, since the operating frequencies of circuits or active/passive elements may be equal to or higher than the millimeter-wave band, the waveguide of the circuits or active/passive elements should not have a lumped element characteristic. Rather, the waveguide of the circuits or active/passive elements should have a distributed element characteristic. Also, since the millimeter-wave band has a frequency dispersion characteristic, designing a waveguide is important for the operation and performance of a millimeter-wave circuit.
In order to transmit or process super high frequencies of a millimeter-wave band with low loss, a low-loss, high-performance waveguide is needed. Waveguide loss includes conductor loss of metals and dielectric loss of dielectrics.
Since the dielectric loss is reduced when the separation distance between a high-loss dielectric substrate and both signal lines and ground lines of a multi-layer metal structure is increased, the nearer the signal lines and ground lines are formed to an uppermost metal layer of the multi-layer metal structure, the less the dielectric loss of the signal lines and ground lines will be. Meanwhile, the lower the conductivity of metals used in the multi-layer metal structure and the more current that flows through a limited region, the greater the conductor loss.
Accordingly, the exemplary embodiments provide a waveguide structure which improves the quality and efficiency of transmission by widening a region through which current flows to minimize loss in a multi-layer metal structure.